Molecular Dynamics Simulation On The Mechanical Properties Of Crystalline Aluminum Under Nanoindentation

With the development of Nanotechnology,domestic and overseas researchers begin to pay more attention to mechanical properties of materials in nano-scale.Nanoindentation has become an important means to study its mechanical properties because of its high precision and many factors that can be studied and analyzed.In this paper,LAMMPS and ATOMSK software are used to complete the simulation of molecular dynamics,and the models of single-crystal aluminum,polycrystalline aluminum,nanotwinned aluminum and nanotwinned polycrystalline aluminum are established.The nanoindentation process is simulated by using EAM and Morse potential function.The influence of different temperature,loading rate and other factors on the structure change and mechanical properties is obtained.The results show that compared with single-crystal aluminum,the dislocation produced by polycrystalline aluminum indentation is mainly the accumulation of dislocation.For nanotwinned aluminum,the dislocations generated by nanoindentation are more concentrated and difficult to pass through the twin boundary.For nanotwinned polycrystalline aluminum,the dislocations at the indenter contact are mainly stacking dislocations.In addition,by changing the experimental factors such as temperature,the effects of different factors on the nano indentation of nano aluminum model are obtained.It is found that the load peak tends to decline with the increase of temperature.With the increase of the rate,the peak load tends to rise.With the increase of the number of twin boundaries,the load peak shows an upward trend.With the increase of the number of grains,the load peak shows a downward trend.The results of this paper provide a theoretical reference for the nanoindentation research of aluminum crystals.